Effect of left bundle branch pacing on left ventricular systolic function and synchronization in patients with third-degree atrioventricular block, assessment by 3- dimensional speckle tracking echocardiography

To explore the effect of left bundle branch pacing (LBBP) on left ventricular systolic function and synchronization in patients with third-degree atrioventricular block.Fifty patients with third-degree atrioventricular block from 2019- to 01-01 to 2019-6-31 in The Affiliated Hospital of Qingdao University who were eligible for pacing indications were selected. According to different pacing locations, they were randomly divided into LBBP group and right ventricular septal pacing (RVSP) group. Three-dimensional speckle tracking technology was used to collect left ventricular global longitudinal strain (GLS), global radial strain (GRS), and global circumferential strain (GCS) before surgery, 6 months after surgery, 12 months after surgery, and 18 months after surgery. At the same time, the percentage of the standard deviation of the time when the left ventricular 16 segments reach the minimum systolic volume in the cardiac cycle (Tmsv16-SD/R-R) was calculated. And the QRS duration of the two groups was followed up.1. GLS in LBBP group and RVSP group after surgery was significantly higher than that before surgery. And GLS in LBBP group and RVSP group showed an upward trend after surgery. However, the increase rate in LBBP group was higher than that in RVSP group. At 18 months after surgery, LBBP group was significantly higher than that in RVSP [(29.92±4.73) vs (26.48±3.80), p<0.05]. GCS in LBBP group increased gradually after surgery. GCS in RVSP group was no significant change after surgery. At 18 months after surgery, GCS in RVSP group was significantly lower than that in LBBP group [(27.92±3.37) vs (29.48±4.40), p<0.05]. There was no significant change in GRS between the two groups(p＞0.05). 2. Tmsv16-SD/R-R in LBBP group and RVSP group after surgery were lower than that before surgery (p<0.05). Tmsv16-SD/R-R in the LBBP group after surgery remained stable (P>0.05). At 18 months after surgery, Tmsv16-SD/R-R was significantly lower than that in the RVSP group [(4.27±0.67) vs (6.34±1.70), P<0.05]. 3. The QRS duration in LBBP group after surgery was significantly lower than that before surgery. And the QRS duration of the patients in the LBBP group remained stable during the 18-month follow-up (P>0.05). The QRS duration in the RVSP group after surgery had no significant change compared with that before surgery.The QRS duration in the LBBP group was significantly lower than that in the RVSP group after surgery (P＜0.05). 4. The LVEF of the LBBP group and the RVSP group remained stable after surgery, and there was no statistical difference between the two groups.As an emerging pacing method, LBBP has good postoperative contractility and can maintain good electromechanical synchronization.